Photoconductors that include photogenerating layers and specific charge transport layers are known. Although these photoconductors may be useful for xerographic imaging and printing systems. many of them have a tendency to deteriorate and thus have to be replaced at considerable costs and with extensive resources. A number of known photoconductors also have a minimum of, or a lack of resistance to abrasion from dust, charging rolls, toner, and carrier. For example, the surface layers of photoconductors are subject to scratches, which decrease their lifetime, and in xerographic imaging systems adversely affect the quality of the developed images. While used photoconductor components can be partially recycled, there continues to be added costs and potential environmental hazards when recycling.
In xerographic systems extending photoreceptor life using robust layers, such as overcoats, can in some instances cause undesirable increased lateral charge migration (LCM) due to lowered wear rates and accumulation of polar and conductive chemical species on the photoconductor and friction between the cleaning blade and the photoconductor surface. Increased friction is particularly pronounced in BCR (biased charging roll) charging systems where friction forces become excessive in that the torque provided by the photoconductor motor is insufficient to even turn the photoconductor drum resulting in a torque failure thereby rendering the xerographic system and machine inoperable. Under these circumstances, the cleaning blade chips and deforms to an extent where it is non-functional and causes cleaning streaks in the xerographic developed electrostatic images.
In addition, imaging members, such as photoconductors, are generally exposed to repetitive xerographic cycling, which subjects the exposed charged transport layer or alternative top overcoat layer thereof to mechanical abrasion, chemical attack and heat. This repetitive cycling causes gradual deterioration in the mechanical and electrical characteristics of the exposed photoconductor surface layer. Physical and mechanical damage during prolonged use, including the formation of surface scratch defects, are examples of reasons for the failure of belt photoconductors.
Thus, there is a need for photoconductors that substantially avoid or minimize the disadvantages of a number of known photoconductors.
Also, there is a need for wear resistant photoconductors with excellent, or acceptable mechanical characteristics, especially in xerographic systems where biased charging rolls (BCR) are used.
There is also a need to improve the mechanical robustness of photoconductors or photoreceptors, and to increase their scratch resistance, thereby prolonging their service life.
Moreover, there is a need for abrasion scratch resistant photoconductive surface layers with, for example, from about 10 percent to about 25 percent wear reduction improvement.
There also remains a need for improved imaging members that are wear resistant, and that provide in combination excellent imaging performance, extended lifetimes, and that possess reduced human and environmental health risks.
Wear resistant long life photoconductors with excellent cyclic characteristics and stable electrical properties, stable long term cycling, minimal charge deficient spots (CDS), and acceptable lateral charge migration (LCM) characteristics, such as excellent LCM resistance, are also desirable needs.
These and other needs are believed to be achievable with the photoconductors disclosed herein.